function  [spline_lon, spline_lat,spline_course]= spline_process(data_input,index_interpolation)
%UNTITLED 此处显示有关此函数的摘要
%   进行三次样条插值
%data_input 输入的原始数据，作为插值样本
%index_interpolation 需要插值点位置

time_diff = data_input.time-data_input.time(1);
lon=data_input.Lon;%原始数据的经纬度和航向角
lat = data_input.Lat;
course = data_input.Course;
spline_lon = spline(time_diff, lon, index_interpolation);%插值获得的经纬度和航向角
spline_lat = spline(time_diff, lat, index_interpolation);
spline_course = spline(time_diff, course, index_interpolation);

% %形象化展示
% figure
% plot(lon,lat,'ro-');
% hold on;
% plot(spline_lon,spline_lat,'b*')


end